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Abstract:

A pane having a heatable, optically transparent sensor array comprising
at least: a) a pane, b) at least one optically transparent sensor array
on the surface of the pane, c) at least one heatable film which is fitted
to the optically transparent sensor array, comprising: c1) a support
film, c2) a heatable coating, printed conductors, meshes and/or heating
wires on the support film, d) at least one electrical contact-making
means, which is fitted to the heatable coating and/or to the heating
wires, and e) encapsulation, which is fitted to the optically transparent
sensor array and to the heatable film, and a sensor which is fitted in
the encapsulation.

Claims:

1. A pane with a heatable, optically transparent sensor array comprising
at least: a pane, at least one optically transparent sensor array on the
surface of the pane at least one heatable film affixed on to the
optically transparent sensor array, the heatable film comprising at
least: a support film, a heatable coating, printed conductors, meshes,
and/or heating wires on the support film, at least one electrical
contacting means affixed to the heatable coating and/or to the heating
wires, and an encapsulation affixed to the optically transparent sensor
array and to the heatable film, and a sensor affixed in the
encapsulation.

14. A method for producing a pane with a heatable, optically transparent
sensor array, comprising: affixing a heatable film comprising a support
film with a heatable coating, printed conductors, meshes and/or heating
wires, on the sensor array on a surface of the pane providing the
heatable film with electrical contacting means and affixing an
encapsulation with a sensor on the heatable film.

15. A method for providing the pane with the heatable, optically
transparent sensor array according to claim 1, the method comprising
installing the pane with the heatable, optically transparent sensor array
in motor vehicles, ships, airplanes, and helicopters, such as a
windshield and/or rear window of a motor vehicle.

16. The pane according to claim 12, wherein the encapsulation is arranged
behind a cover strip.

Description:

[0001] The invention relates to a pane with a heatable, optically
transparent sensor array, a method for production thereof, and use
thereof.

[0002] Many motor vehicles, airplanes, helicopters, and ships are equipped
with various optical sensors. Examples of optical sensors are camera
systems, such as video cameras, night vision cameras, residual light
amplifiers, or passive infrared detectors such as FUR (forward looking
infrared). The camera systems can use light in the ultraviolet (UV),
visible (VIS), and infrared wavelength range (IR). Thus, they make it
possible, even under poor weather conditions, such as darkness and fog,
to precisely detect objects, motor vehicles, as well as persons. In motor
vehicles, these camera systems can be placed behind the windshield inside
the passenger compartment. Thus, they offer the capability of detecting
hazardous situations and obstacles in a timely manner even in road
traffic.

[0003] Other areas that use optical sensors include electronic distance
measurement (EDM), for example, using laser distance meters. The distance
to other motor vehicles can be determined Such systems are common in the
military field of application, but there are also many possibilities for
civilian use. By measurements of the distance to the preceding vehicle,
it is possible to determine the necessary safety distance and to
significantly increase traffic safety. With automatic warning systems,
the danger of a rear-end collision is significantly reduced.

[0004] Because of their sensitivity to weather influences or airstreams,
such sensors must in all cases be protected by appropriate panes. The
sensor can either be installed inside a motor vehicle or outside as in
the case of thermal imaging cameras of helicopters. In that case, the
sensor is installed in a pivotable housing outside on the helicopter. In
order to ensure optimum functioning of the optical sensor, with both
options, clean, condensation-free panes are absolutely essential.
Condensation and icing significantly interfere with functioning, since
they significantly reduce the transmission of electromagnetic radiation.
Whereas wiper systems can be used for drops of water and dirt particles,
these are usually inadequate with icing. Systems that heat the segment of
the pane associated with the sensor at least briefly as needed and thus
enable uninterrupted use are essential. In order to keep energy
consumption and the voltage needed low, only the field of vision of the
pane necessary for the sensor should be heated in this manner.

[0005] Besides the external surface of the pane, the inside pane must,
above all, be kept free of condensation. So that no dirt and dust
particles foul the sensors, the sensor and pane arrangement are usually
encapsulated. If moisture penetrates into this encapsulated space, this
moisture can, especially with cold outside temperatures, condense on the
inside of the pane and restrict the functionality of the sensor.

[0006] DE 10 2007 001 080 A1 discloses an electrically heatable window
pane. This is supplied with current using electrical bus bars and thus
heated. The arrangement of the bus bars is such that only small
electromagnetic fields are developed. Thus, operation of devices that
react sensitively to electromagnetic fields is possible even in the
region of the pane.

[0007] DE 101 56 850 A1 discloses a sensor in a motor vehicle window pane,
whose lens is sealed off from the motor vehicle interior by
encapsulation. This configuration prevents the deposition of dust
particles on the lens. A particle filter is provided for air exchange.

[0008] DE 10 2004 054 161 A1 discloses an infrared light detection area in
a motor vehicle windshield. The infrared light detection area is
surrounded by heating elements that keep it ice and condensation free by
heat conduction. EP 1 605 729 A2 discloses an electrically heatable pane
with a camera window. This camera window is kept condensation and ice
free by means of a heating device. The heating element is laminated into
the pane at the position of the camera window. In addition, another
additional heating element can be applied on the pane surface. The
additional heating element is preferably printed onto the pane surface as
a conductive paste.

[0009] The object of the invention is to provide a pane with a heatable,
optically transparent sensor array that can be produced easily from
finished, standardized panes without major modifications.

[0010] The object of the present invention is accomplished according to
the invention by a pane with a heatable, optically transparent sensor
array, a method for production thereof, and use thereof according to the
independent claims 1, 14, and 15. Preferred embodiments emerge from the
subclaims.

[0011] The pane with a heatable, optically transparent sensor array
comprises at least a pane and at least an optically transparent sensor
array. In the context of the invention, the expression "optically
transparent sensor array" refers to the part of the pane that supplies
the sensor with the relevant optical and electromagnetic data or signals.
This can be any part of the pane or an inserted pane segment that has
high transmission for the relevant optical and electromagnetic signals.
The characteristic "optically transparent" refers, in the context of the
invention, to the wavelength range from 200 nm to 2000 nm, preferably 400
nm to 1300 nm. The transmission is preferably more than 70% in the
wavelength range from 400 nm to 1300 nm.

[0012] The optically transparent sensor array preferably occupies less
than 10%, particularly preferably less than 5% of the surface of the
pane. The heatable film arranged on the optically transparent sensor
array comprises at least a support film, a heatable coating, printed
conductors (e.g., screen printing or inkjet printing), meshes (e.g., a
copper coating structured by etching), and/or heating wires as well as an
electrical contacting means affixed on the heatable coating, printed
conductors, meshes, and/or the heating wires. In the context of the
invention, the heatable coating, printed conductors, meshes, and/or the
heating wires can be affixed both on the side of the support film facing
the pane and also and/or on the side of the support film turned away from
the pane. The support film preferably has a thickness of 20 μm to 500
μm, particularly preferably from 30 μm to 200 μm. The heatable
coating, printed conductors, meshes, and/or heating wires function as
electrical resistors and are affixed directly on the film. The layer
thickness or wire thickness is defined based on the necessary heat
output. The heating wires preferably have a thickness of 10 μm to 100
μm; the electrical coating preferably has a sheet resistance of 0.5
ohms per square to 3 ohms per square, with a voltage of 12 V to 15 V. The
averaged transmission of the entire arrangement of sensor array and
heatable film is preferably more than 60%, particularly preferably more
than 70%.

[0013] An encapsulation and a sensor affixed in the encapsulation are
mounted on the optically transparent sensor array and the heatable film.
The encapsulation protects the sensor from dirt and dust particles as
well as unwanted incidence of light. The encapsulation is preferably
arranged in the upper region of the pane, preferably not farther than 30%
of the height of the pane from the top and/or bottom edge. The
encapsulation preferably contains a polymer, particularly preferably
polybutylene terephthalate, polyamides, polycarbonate, polyurethanes,
polybutylene, polypropylene, polyethylene, polyethylene terephthalate,
polyvinyl chloride, polystyrene, acrylonitrile butadiene styrene,
ethylene vinyl acetate, ethylene vinyl alcohol, polyimides, polyester,
polyketones, polyether ether ketones, and/or polymethyl methacrylate, as
well as mixtures, block polymers, and copolymers thereof.

[0014] The sensor preferably comprises cameras for visible light of
wavelengths from 400 nm to 800 nm and infrared light of wavelengths from
800 nm to 1300 nm.

[0023] The heatable film preferably contains an optically transparent
antistatic, water absorbing, hydrophilic, hydrophobic, or lipophobic and
hydrophobic coating. Examples of hydrophilic coatings of polyester films
are found in EP 1 777 251 A1. Coating solutions for hydrophilic coatings
contain, for example, sulfopolyester of 90 mol-% isophthalic acid and 10
mol-% sodium sulfoisophthalic acid as well as a surface active agent such
as diethylhexyl sulfosuccinate-sodium salt (AOTI with, in each case, 1
wt.-% to 5 wt.-%. Coatings with halogenated hydrocarbons, in particular
with --CHT--, --CF2--, and --CF3 groups make possible a coating
that is both lipophobic, repelling fat or nonpolar hydrocarbons, and also
hydrophobic, repelling water. Water absorbing coatings include, for
example, swellable hydrophilic polymers such as polysaccharides,
cellulose derivatives, and polyethylene oxides.

[0025] The encapsulation is preferably affixed in the upper region of the
windshield and/or the rear window, particularly preferably behind a cover
strip, a sun visor, and/or a band filter. In this configuration, a recess
is preferably arranged for the optically transparent sensor array.

[0026] The encapsulation preferably contains water absorbing materials or
desiccants, particularly preferably silica gel, CaCl2, activated
charcoal, silicates, bentonites, zeolites, and/or mixtures thereof. The
desiccants can be incorporated into the surface of the encapsulation
and/or arranged in open receptacles in the encapsulation. The desiccants
are preferably arranged such that air and moisture exchange with the air
in the interior of the encapsulation is possible, but the materials
cannot fly around and are affixed. This can preferably occur by enclosing
the desiccants in an air and moisture permeable polymer film or in a
fine-meshed net. The invention further includes a method for producing a
pane with a heatable, optically transparent sensor array. In a first
step, the support, film is provided with a heatable coating, printed
conductors, meshes, and/or heating wires. The heatable film obtained is
mounted on a sensor array of a pane. The attachment of the heatable film
preferably occurs as self-adhesive film or using an optically transparent
adhesive. A cover layer made of a polymer film is preferably applied on
the heatable film. The cover layer preferably contains PYB, EVA, PET,
and/or mixtures thereof. The cover layer is preferably arranged
overhangingly, such that the support film and the heatable coating are
laminated onto the pane surface using the cover layer.

[0027] The invention further includes the use of the pane with a heatable,
optically transparent sensor array according to the invention in motor
vehicles, ships, airplanes, and helicopters.

[0028] The pane with a heatable, optically transparent sensor array is
preferably used as a windshield and/or rear window of a motor vehicle.

[0029] In the following, the invention is explained in detail with
reference to a drawing. The drawing in no way restricts the invention.

[0030] The figures depict:

[0031] FIG. 1 a plan view of the pane (1) according to the invention,

[0032] FIG. 2 a cross-section of a preferred embodiment of the pane (1)
with a heatable, optically transparent sensor array (2) according to the
invention,

[0036] FIG. 1 depicts a plan view of the pane (1) according to the
invention. A heatable film (3) is arranged on an optically transparent
sensor array (2). The optically transparent sensor array (2) comprises
the part of the pane (1) that supplies the sensor (7) depicted in FIG. 2
with the relevant optical and electromagnetic data or signals. This can
be any part of the pane (1) or an inserted pane segment that has high
transmission for the relevant optical and electromagnetic signals. The
heatable film (3) is connected to an electrical contacting means (4) that
is connected to a power source, for example, an automobile battery.

[0037] FIG. 2 depicts a cross-section along the height of the pane I to I'
in FIG. 1 of a preferred embodiment of the pane (1) according to the
invention with a heatable, optically transparent sensor array (2). In the
region of the optically transparent sensor array (2), a heatable film (3)
is arranged on the interior side of the pane (1). The sensor (7) oriented
toward the optically transparent sensor array (2) is located inside an
encapsulation (6) mounted on the optically transparent sensor array (2).
Desiccants (8) are arranged inside the encapsulation (6). The desiccants
(8) are preferably incorporated into the surface of the encapsulation
(6).

[0038] FIG. 3 depicts a cross-section of the heatable, optically
transparent sensor array (2). The heatable film (3) is arranged with the
electrical contacting means (4) on the optically transparent sensor array
(2). The heatable film (3) comprises a support film (3a) and, on the side
of the support film (3a) turned away from the optically transparent
sensor array (2), a heatable coating (3b) and/or heating wires (3c).
These can be applied with conventional techniques such as chemical vapor
deposition (CND) or physical vapor deposition (PVD), such as cathodic
sputtering (sputtering).

[0039] FIG. 4 depicts a cross-section of another embodiment of the
heatable, optically transparent sensor array (2). The heatable film (3)
with the electrical contacting means (4) is arranged on the optically
transparent sensor array (2). The heatable film (3) comprises a support
film (3a) and, on the side of the support film (3a) facing the optically
transparent sensor array (2), a heatable coating (3b) and/or heating
wires (3c). These can be applied with conventional techniques such as
chemical vapor deposition (CVD) or physical vapor deposition (PVD), such
as cathodic sputtering (sputtering).

[0040] FIG. 5 depicts a cross-section of a preferred embodiment of the
heatable, optically transparent sensor array (2). The heatable film (3)
with the electrical contacting means (4) is arranged on the optical pane
segment. The heatable film (3) comprises a support film (3a) and a
heatable coating (3b) and/or heating wires (3c). A cover layer (3d) made
of a polymer film is arranged on the heatable coating (3b) and/or heating
wires (3c). The cover layer (3d) is preferably arranged overhangingly,
such that the support film (3a) and the heatable coating (3b) are
laminated and affixed over the cover layer (3d) on the pane surface (1,
2). The cover layer (3d) contains an antistatic, hydrophilic,
hydrophobic, or lipophobic and hydrophobic coating (3e).